Applicability of Different Antibodies for Immunohistochemical Localization of CFTR in Sweat Glands from Healthy Controls and from Patients with Cystic Fibrosis

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Abstract
The hereditary disease cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Understanding of the consequences of CFTR gene mutations is derived chiefly from in vitro studies on heterologous cell cultures and on cells hyperexpressing CFTR. Data from ex vivo studies on human tissue are scarce and contradictory, a fact which is in part explained by secondary tissue destruction in most affected organs. The purpose of this study was to establish conditions under which wild-type and mutated CFTR can be studied in affected human tissue. Sweat glands carry the basic defect underlying CF and are not affected by tissue destruction and inflammation. Therefore, we used this tissue to test a panel of eight different CFTR antibodies under various fixation techniques. The antibodies were tested on skin biopsy sections from healthy controls, from CF patients homozygous for the most common mutation, ΔF508, and from patients carrying two nonsense mutations. Of the eight CFTR antibodies, only three—M3A7, MATG 1104, and cc24—met the criteria necessary for immunolocalization of CFTR in sweat glands. The labeling pattern in the CF sweat glands was consistent with the postulated processing defect of ΔF508 CFTR. The antibodies exhibited different sensitivities for detecting ΔF508 CFTR.